Two 500 MW units trip at NTPC unit

HYDERABAD Sept. 21. Power supply in the State was partially disrupted as two 500 MW units tripped at the Simhadri plant of National Thermal Power Corporation (NTPC) around midnight on Saturday but one of them was brought back into generation on Saturday afternoon.

Submergence of all the discharge valves of the circulating water pumps was the cause of the tripping which also resulted in a dip in the frequency of power levels from 49.52 to less than 48.5 hz. An emergency load relief was immediately arranged to improve the frequency to around 49 hz to protect the grid from collapse, a press release of AP TRANSCO said.

The NTPC is making all efforts to put the other unit also back into generation as early as possible, the statement added. To make up for the loss of generation on account of the tripping of two units, the TRANSCO contacted Southern Regional Load Despatch Centre and increased the import of power from the eastern region to 650 MW. A hydel generation of 400 MW was also made for further safety of the grid. The balance of generation was met by regulating the loads.

Incidentally, it was on Saturday that TRANSCO met an energy demand of 140 MU as against a demand of 121 MU on the same day last year.

A separate TRANSCO press release said its Chairperson and Managing Director, Rachel Chatterjee, has written a letter to the employees commending their efforts in maintaining satisfactory levels of supply despite a dry spell, which affected hydel generation. TRANSCO was forced to purchase power at a high rate from thermal and gas stations to meet the demand.

The hydel-thermal mix in the supply, which was expected to be 20:80 at the commencement of the year fell to 5:95 by September due to poor inflows into reservoirs. The hydel-thermal mix was 35:65 in 1995-96, while the average daily demand itself was 97 MU. But, the power utilities are able to meet an average daily demand of 140 to 150 MU currently despite such poor hydel-thermal mix.

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